Unable to export object to 3ds file
Your models exceeded the max polygon limit for 3ds files, which is currently 65536. I've decimated the models for you to go below that number. You can download the zip here:

https://www.dropbox.com/s/mwxzr447792digb/Dragons.zip?dl=0

If you would like a more detailed explanation regarding 3ds exporting please visit this thread:

Export object to a 3ds file error

Have a nice day!